Compositions adapted for chain linking

ABSTRACT

A polymer composition comprising chains of at least one aromatic polymer or a mixture thereof together with at least one chain linking component wherein the at least one aromatic polymer comprises polymer chains of number average molecular weight (Mn) in a first range and characterised by a polymer flow temperature, and having at least one reactive end group, and wherein the at least one chain linking component comprises at least two linking sites, characterised in that a plurality of the polymer chain end groups are adapted to react with the linking sites at chain linking temperature in excess of the polymer flow temperature to form linked polymer chains of number average molecular weight (Mn) in a second range which is in excess of the first range, substantially thermoplastic in nature; process for the preparation thereof; prepreg, composite or shaped product obtained therewith and the use thereof.

[0001] The present invention relates to polymer compositions, prepregs,laminar composites and shaped articles adapted for chain linking inmanner to increase the number average molecular weight thereof, aprocess for the preparation and shaping thereof, a process for the chainlinking thereof. Specifically the present invention relates topolyaromatic compositions, prepregs, laminar composites and shapedarticles.

[0002] The use of curable compositions such as epoxy, cyanate, phenolicand like resins, both reinforced and unreinforced, has been known for along time in a wide variety of structural commercial and militaryapplications. In constructing sports devices, building materials,aeronautical, land and nautical vehicles, light weight carbon-basedtough materials have been found to give enhanced performance. Moreoverthese compositions are found to have uses as high temperature curingadhesives.

[0003] More recently, classes of polyaromatic compositions comprisingpolyaryl thermoplastic components containing ether- and/orthioether-linked repeating units in the form of polyether aromatics andpolyetherether aromatics are known for the manufacture of engineeringpolymers and composites having unique properties in terms of strength,fracture toughness, modulus and high temperature stability andresistance. In particular the semi-crystalline polyaryl components haveexcellent solvent resistance properties.

[0004] These polymer compositions are typically prepared at temperaturesin excess of their crystalline melt temperature, e.g. in the range of upto 365° C., formed with autoclaving into prepregs, composites or shapedarticles and subsequently processed at elevated temperature and/or withuse of a curing agent. There is a trade off between the advantageoussolvent resistance of semi-crystalline compositions and their highprocessing temperature. It would therefore be advantageous to be able toprovide semi-crystalline compositions which may be processed at lowertemperatures, whereby their use could become more accessible formanufacture of articles.

[0005] The quality of prepregs, composites or shaped articles obtainedwith these compositions is dependent on a number of factors, not leastthe rheology thereof, in terms of ease and uniformity of impregnation,molding or shaping, together with ability to be retained in impregnated,molded or shaped form without distortion prior to and during processingof impregnated, molded or shaped articles.

[0006] Typically there is a trade off between providing compositionswith sufficiently low viscosity to enable complete and accurateimpregnation, molding or shaping thereof but with acceptable mechanicalproperties in processed form, against an excessively high viscosity atwhich impregnation, molding and shaping performance deterioratesexcessively.

[0007] Attempts to improve processing and mechanical performance of suchcompositions have focussed on modification of the nature of components,for example, including a blend of thermoplast and thermoset componentsto optimise the processed mechanical properties or modification of themethod for impregnating, molding or shaping, for example, in solution ofa suitable solvent which may subsequently be evaporated prior toprocessing. These attempts, however introduce further problems in termsof morphology control, solvent resistance and void formation forexample.

[0008] In “Polyaromatics”, P. T. McGrail, Polymer International 41(1996) 103-121, polyaromatics and their synthesis and properties arereviewed. In particular the above problems in terms of prepregging, forexample from solution, and properties of processed prepregs arediscussed with reference to block copolymers comprising blocks ofdistinct polymer types linked via reactive pendant groups andfunctionalised polyaromatics having reactive groups adapted forcross-linking are discussed. This comprehensive review of currentlyavailable techniques discloses the compromises which must be made andproblems which are encountered in the manufacture of engineeringpolymers from fluid compositions.

[0009] We have now surprisingly found however that polymer compositionsmay be provided which overcome the problems described above in admirablemanner, having excellent Theological properties for prepregging, moldingand shaping into articles, combined with excellent mechanical andsolvent resistance properties as engineering polymers.

[0010] Accordingly a first object of the present invention is to providepolyaromatic compositions for making molded, impregnated or otherwiseshaped articles for which mechanical properties of processed molded,impregnated or otherwise shaped articles may be controlled independentlyof constraints imposed by rheology required for effective injectionmolding, impregnation or shaping to form articles.

[0011] A second object of the present invention is to providepolyaromatic compositions prepared in a calculated molecular weightrange of polymer which may be achieved independently of constraintsimposed by the preparation process, such as solubility constraints andthe like.

[0012] A third object of the present invention is to providepolyaromatic compositions with a desired level of uniform mobility toprovide a desired increase in number average molecular weight on furtherreaction thereof.

[0013] A fourth object of the present invention is to provide highquality injection molded, impregnated or otherwise shaped articles ofessentially thermoplastic polymers obtained with improved properties offinished articles and having improved solvent resistance propertieswithout the commonly associated high processing temperatures requiredfor molding, impregnation or otherwise shaping thereof.

[0014] In its broadest aspect there is provided according to the presentinvention aromatic polymer compositions having rheology adapted forimpregnation, is molding or otherwise shaping and being adapted forsubsequent reactive chain linking thereof to provide polymercompositions of increased molecular weight which are substantiallythermoplastic in nature.

[0015] Specifically there is provided according to the present inventiona polymer composition comprising chains of at least one aromatic polymeror a mixture thereof together with at least one chain linking componentwherein the at least one aromatic polymer comprises polymer chains ofnumber average molecular weight (Mn) in a first range and characterisedby a polymer flow temperature, and having at least one reactive endgroup, and wherein the at least one chain linking component comprises atleast two linking sites, characterised in that a plurality of thepolymer chain end groups are adapted to react with the linking sites atchain linking temperature in excess of the polymer flow temperature toform linked polymer chains of number average molecular weight (Mn) in asecond range which is in excess of the first range, substantiallythermoplastic in nature.

[0016] The polymer composition as hereinbefore defined may be adaptedfor prereaction to form a precursor composition comprising an amount ofat least one aromatic polymer as hereinbefore defined, together with anamount thereof, which has been prereacted at chain terminatingconditions with the at least one chain linking component as hereinbeforedefined to form polymer chains of Mn in the first range, characterisedby a polymer flow temperature and having its reactive end groupsterminated with linking component, characterised in that a plurality ofthe polymer chain reactive end groups are adapted to react with thelinking sites of linking component terminated polymer chains at chainlinking temperature in excess of the polymer flow temperature to formlinked polymer chains of number average molecular weight (Mn) in asecond range which is in excess of the first range.

[0017] Flow temperature is defined as the temperature at which thepolymer attains a suitably molten or fluid state to enable a degree ofpolymer chain mobility to orient or align itself for reaction.

[0018] Chain linking temperature is defined as the temperature at whichthe polymer chain ends reaction is initiated. Preferably the chainlinking temperature is higher than a product processing temperature, toremove solvent and improve wet out of the prepreg which leads to betterquality prepreg with easier handling characteristics.

[0019] Chain terminating conditions may be selected such that selfreaction is avoided, ie whereby the chain termination does not developinto a chain linking reaction.

[0020] The composition is adapted for shaping with reduced physical voidformation as a result of the greater and more uniform mobility of thecomposition having Mn in a first range. This is particularlyadvantageous and enables high through put laminate production withouttemperature ramping or degassing.

[0021] The difference in first and second Mn ranges is defined as theincrease at which a desired extent of reaction is achieved by means ofchoice of stoichiometry, reaction time or temperature at which mobilitydecreases as a result of reaction below that for polymer chains to alignthemselves for further reaction. It will be appreciated therefore thatthe second Mn range may be controlled by selection of stoichiometry orreaction time or of chain linking temperature with respect to the flowtemperature and with respect to any postcure temperature applied.

[0022] The number average molecular weight of the polyaromatic in thesecond range is suitably in the range 9000 to 60000. A useful sub-rangeis for example 11000 to 25000, and in the first range is suitably in therange of 2000 to 11000, especially in the range of 3000 to 9000.

[0023] The composition may comprise an additional solvent for thepolymer chains whereby a reduced flow temperature may be attained.Preferably the composition comprises substantially no solvent and isadapted for flow and chain linking in the absence of any solvent oreffective amount thereof. It is a particular advantage that compositionscomprising no solvent are adapted to retain the polymer chain morphologyin the chain linked form.

[0024] It is a particular advantage of the invention that thecompositions are adapted for forming articles at low temperature due totheir flowable rheology in unreacted form giving excellent moulding,impregnation wet out or shaping complexity (with injection moulding),and in reacted form having number average molecular weight in a secondrange as hereinbefore defined they are characterised by mechanical andthermal properties corresponding to known compositions comprisingpolymer chains having number average molecular weight in the secondrange as hereinbefore defined. This allows the use of cheaper bagging,moulding, tie-down or other ancillary materials.

[0025] Preferably compositions comprising two or more aromatic polymerscomprise a first and second polymers having the same polymer backbonebut different end groups, both being amorphous, or comprise a firstaromatic polymer having a lower flow temperature than a second similararomatic polymer, both being amorphous the second polymer being renderedin flowable form in the presence of the first polymer in fluid form,thereby providing a processing aid, or comprise an amorphous polymer anda semi crystalline polymer having a characteristic melting point, thesemi crystalline polymer being rendered flowable by solvent effect ofthe first polymer, and is not truly molten at a temperature below thatat which it is normally processable as determined by its characteristicmelting point.

[0026] More preferably a second aromatic polymer is (semi)crystallineand is rendered in flowable form by solvating action of a firstamorphous aromatic polymer. Accordingly the first aromatic polymer mayact as a cosolvent, diluent, dispersant, carrier or the like for thesecond aromatic polymer. This is of particular advantage in enabling thepreparation of multiblock compositions having lowered processingtemperatures whilst nevertheless retaining excellent product propertiessuch as solvent resistance. It is of significance that the productexhibits (semi)crystalline morphology, which is responsible forexcellent solvent resistance of some product polymers of the invention.

[0027] Reactive end groups and chain linking sites as hereinbeforedefined are suitably any functional groups adapted to be inert at lowtemperature and to mutually react at elevated temperature in manner tolink the polymer chains and linking component and effect chain linking.End groups and chain linking sites may be the same, in the case of selfreacting functionalities, or may be different in the case of differentreacting functionalities.

[0028] Reactive end groups (Y) and chain linking sites (Z) are selectedfrom any functional groups providing active hydrogen and any polarfunctional group adapted to react at elevated temperature in thepresence of an electrophile, preferably selected from active H, OH, NH₂,NHR or SH wherein R is a hydrocarbon group containing up to 8 carbonatoms, epoxy, (meth)acrylate, iso)cyanate, isocyanate ester, acetyleneor ethylene as in vinyl or allyl, maleimide, anhydride, carboxylic acid,oxazoline and monomers containing unsaturation; preferably reactive endgroups Y are selected from active H, OH, NH₂, NHR or SH and chainlinking sites Z are selected from epoxy, (meth)acrylate, (iso)cyanate,isocyanate ester, acetylene or ethylene as in vinyl or allyl, maleimide,anhydride, carboxylic acid, oxazoline and monomers containingunsaturation.

[0029] Preferably a chain linking component is of the formulaB(Z)n(Z′)n′ wherein B is a polymer chain or is a carbon atom backbonehaving from 1 to 10 carbon atoms, more preferably is an oligomer orpolymer or is an aliphatic, alicyclic or aromatic hydrocarbon optionallysubstituted and/or including heteroatoms N,S,O or is a single bond ornucleus such as C, O, S, N or Transition metal; Z and Z′ are eachindependently selected from functional groups as hereinbefore definedfor Z;

[0030] n and n′ are each zero or a whole number integer selected from 1to 6; and

[0031] the sum of n and n′ is at least 2, preferably 2 to 10,000, morepreferably 2 to 10 or 10 to 500 or 500 to 10000.

[0032] More preferably a chain linking component is selected from theformula B(Z)n wherein B and Z are as hereinbefore defined and n isselected from 2 to 6.

[0033] Accordingly it will be apparent that self reaction betweenmethacrylate ended polymer and chain linking component or betweenmaleimide ended polymer and chain linking component or between oxazolineended polymer and chain linking component for example is possible andwithin the scope of the present invention.

[0034] It is possible that a small amount of polymer chains and chainlinking component have mixed reactive end groups and chain linkingsites, ie one of each of the above defined groups, whereby in arelatively mobile early stage of the chain linking reaction, the endgroups and sites are able to seek each other out by alignment of thepolymer chains and chain linking components. Preferably however reactiveend groups are of one type and chain linking components are of a secondtype.

[0035] A polymer chain comprises at least one reactive end group wherebyat least one end may be linked to other polymer chains. Preferably alinear or branched polymer chain having at least two ends comprises atleast two reactive end groups. Reactive end groups may be the same ordifferent and are preferably the same, whereby a polymer chain is termeda diol, polyol, diamine, polyamine, dithiol or polythiol or the like.

[0036] A chain linking component comprises at least two linking siteswhereby at least two polymer chains may be linked together. Preferably achain linear-linking component comprises two linking sites, and a chainnetwork-linking component such as a “star” architecture linkingcomponent comprises at least three linking sites. Linking sites may bethe same or different and are preferably the same, whereby a linkingcomponent is termed a diepoxy, polyepoxy, di(meth)acrylate,poly(meth)acrylate, di(iso)cyanate, poly(iso)cyanate, diacetylene,polyacetylene, dianhydride, polyanhydride, dioxazoline, polyoxazoline orthe like.

[0037] A chain linking component is therefore selected from anycomponent which is capable of supporting multiple functionality in closeproximity, in manner that the multiple functional groups are capable ofreaction. The component comprises a carbon atom backbone or polymerchain linking the linking sites as hereinbefore defined, and linkingsite may be supported as pendant and/or end groups of a linear, cyclicor combined linear-cyclic backbone.

[0038] In a further aspect of the invention there is therefore provideda novel chain linking component as hereinbefore defined. Preferredlinking components are selected from the structures:

[0039] Benzophenone tetra carboxylic acid dianhydride (BTDA)

[0040] Maleic anhydride having units

[0041] In one preferred embodiment the reactive end group is hydroxy andcorresponds to a linking site functionality which is epoxy, wherebyreaction thereof produces a β hydroxy ether linkage in polymers ofincreased number average molecular weight having either hydroxy or epoxyend groups as desired. Alternatively, the reactive end group is NH₂ andthe linking site functionality is anhydride, whereby reaction thereofproduces an imide linkage in polymers of increased number averagemolecular weight having NH₂ or anhydride end groups. Alternatively thereactive end group is NH₂ and the linking site functionality ismaleimide. Mixtures of the above may be employed to produce a mixedarchitecture including a plurality of reactive end group-linking sitecombinations.

[0042] Aromatic polymer chains have at least one reactive end group ashereinbefore defined, and linking components have at least two linkingsites. The reactive end groups and linking sites may be present,calculated by the amount of polymer chain and linking component, in therequired stoichiometric amounts to enable up to 100% linking of polymerchains in multiples of two (binary linking), three (tertiary linking),four (ternary linking), for example in a “star” architecture, andcombinations thereof. Preferably amounts are calculated to give 80-100%linking, more preferably 90-100% linking, most preferably 95-100%linking, for example substantially 100% linking, or may be present withone or other in excess.

[0043] An amount of a single ended or end capping component or polymerchain may be present to end cap the linked chains, and may be the sameor different from the polymer chain or linking component.

[0044] Compositions comprising more than one aromatic may comprisearomatics each having a different type of end groups or may comprise allaromatics having the same type(s) of end groups as hereinbefore defined.One or more chain linking components may be provided with the same ordifferent linking site functionality.

[0045] Preferably each polymer chain present in the composition hasreactive end groups of the same type whereby reaction can take placewithout any specific orientation of polymer chains with respect to chainlinking component. It is a particular advantage that polymer chains maybe to an extent self-orientating in that reactive end groups of thepolymer chains have an affinity for linking sites of the chain linkingcomponent.

[0046] Block copolymers may be generated by chain linking differentpolymer chain types, having the same or different reactive end groups,adapted to alternate in desired manner.

[0047] An amount of additional intra or inter chain functionality may beprovided in the form of functional groups along the chain length.Accordingly the chain linking component may be selected to provide suchfunctionality, for example as solvent resistance (F), cross-linkinggrafting sites (unsaturated groups), Tg enhancing or compatibilisingagents eg a microstructure compatible and reactive with another polymer.

[0048] It is a particular advantage that the compositions of theinvention may be provided in distinct forms having characteristic numberaverage molecular weight as hereinbefore defined.

[0049] Preferably the at least one polyaromatic comprises same ordifferent repeating units of the formula

[0050] wherein A is selected from SO₂, a direct link, oxygen, sulphur,—CO— and a divalent hydrocarbon radical;

[0051] X is a divalent group;

[0052] R is any one or more substituents of the aromatic rings, eachindependently selected from hydrogen, C₁₋₈ branched or straight chainaliphatic saturated or unsaturated aliphatic groups or moietiesoptionally comprising one or more heteroatoms selected from O, S, N, orhalo for example Cl or F; and groups providing active hydrogenespecially OH, NH₂, NHR— or —SH, where R— is a hydrocarbon groupcontaining up to eight carbon atoms, or providing other cross-linkingactivity especially epoxy, (meth) acrylate, cyanate, isocyanate,acetylene or ethylene, as in vinyl, allyl or maleimide, anhydride,oxazoline and monomers containing unsaturation; and

[0053] wherein said at least one polyaromatic comprises reactive pendantand/or end groups preferably selected from reactive heteroatoms,heteroatom containing or cross-linking groups as defined for R.

[0054] Suitably the at least one polyaromatic comprises ether-linkedand/or thioether-linked repeating units, the units being selected fromthe group consisting of

—(PhAPh)_(n)—

[0055] and optionally additionally

—(Ph)_(n)—

[0056] wherein A is SO₂, or CO, Ph is phenylene, n=1 to 2, a=1 to 4 andwhen a exceeds 1, said phenylenes are linked linearly through a singlechemical bond or a divalent group other than —A— or are fused togetherdirectly or via a cyclic moiety such as a cycloalkyl group, a (hetero)aromatic group, or cyclic ketone, amide, amine, or imine, said at leastone polyarylsulphone having reactive pendant and/or end groups.

[0057] More preferably the at least one polyaromatic comprises at leastone polyaryl sulphone comprising ether-linked repeating units,optionally additionally comprising thioether-linked repeating units, theunits being selected from the group consisting of

—(PhSO₂Ph)_(n)—pos

[0058] and optionally additionally

—(Ph)_(a)—

[0059] wherein Ph is phenylene, n=1 to 2, a=1 to 3 and when a exceeds 1,said phenylenes are linked linearly through a single chemical bond or adivalent group other than —SO₂— or are fused together, provided that therepeating unit —(PhSO₂Ph)_(n)— is always present in said at least onepolyarylsulphone in such a proportion that on average at least two ofsaid units —(PhSO₂Ph)_(n)— are in sequence in each polymer chainpresent, said at least one polyarylsulphone having reactive pendantand/or end groups.

[0060] Preferably the polyaromatic comprises polyether sulphone, morepreferably a combination of polyether sulphone and polyether ethersulphone linked repeating units, in which the phenylene group is meta-or para- and is preferably para and wherein the phenylenes are linkedlinearly through a single chemical bond or a divalent group other thansulphone, or are fused together. By “fractional” reference is made tothe average value for a given polymer chain containing units havingvarious values of n or a.

[0061] Additionally, as also discussed, in said at least onepolyarylsulphone, the relative proportions of the said repeating unitsis such that on average at least two units (PhSO₂Ph)_(n) are inimmediate mutual succession in each polymer chain present and ispreferably in the range 1:99 to 99:1, especially 10:90 to 90:10,respectively. Typically the ratio is in the range 25-50 or morepreferably in the range 75-50 (Ph)_(a), balance (Ph SO₂Ph)_(n). Inpreferred polyarylsulphones the units are:

[0062] I X Ph SO₂ Ph X Ph SO₂ Ph (“PES”) and

[0063] II X (Ph)_(a) X Ph SO₂ Ph (“PEES”)

[0064] where X is O or S and may differ from unit to unit; the ratio isI to II (respectively) preferably between 10:90 and 80:20 especiallybetween 10:90 and 55:45, more especially between 25:75 and 50:50; or theratio is between 20:80 and 70:30, more preferably between 30:70 and70:30, most preferably between 35:65 and 65:35.

[0065] The flow temperature of polyetherethersulphone is generally lessthan that of a corresponding Mn polyethersulphone, but both possesssimilar mechanical properties. Accordingly the ratio may be determined,by determining a and n above.

[0066] In copending UK patent application no. 9803714.6 is disclosed aprocess for the obtaining such compositions from their monomerprecursors in manner to isolate the monomer precursors in selectedmolecular weight as desired.

[0067] The preferred relative proportions of the repeating units of thepolyarylsulphone may be expressed in terms of the weight percent SO₂content, defined as 100 times (weight of SO₂)/(weight of average repeatunit). The preferred SO₂ content is at least 22, preferably 23 to 25%.When a=1 this corresponds to PES/PEES ratio of at least 20:80,preferably in the range 35:65 to 65:35.

[0068] The above proportions refer only to the units mentioned. Inaddition to such units the polyarylsulphone may contain up to 50especially up to 25% molar of other repeating units: the preferred SO₂content ranges (if used) then apply to the whole polymer. Such units maybe for example of the formula

[0069] as hereinbefore defined, in which A is a direct link, oxygen,sulphur, —CO— or a divalent hydrocarbon radical. When thepolyarylsulphone is the product of nucleophilic synthesis, its units mayhave been derived for example from one or more bisphenols and/orcorresponding bisthiols or phenol-thiols selected from hydroquinone,4,4′-dihydroxybiphenyl, resorcinol, dihydroxynaphthalene (2,6 and otherisomers), 4,4′-dihydroxybenzophenone, 2,2′-di(4-hydroxyphenyl)propaneand -methane.

[0070] If a bis-thiol is used, it may be formed in situ, that is, adihalide as described for example below may be reacted with an alkalisulphide or polysulphide or thiosulphate.

[0071] Other examples of such additional units are of the formula

[0072] in which Q and Q′, which may be the same or different, are CO orSO₂; Ar is a divalent aromatic radical; and n is 0, 1, 2, or 3, providedthat n is not zero where Q is SO₂. Ar is preferably at least onedivalent aromatic radical selected from phenylene, biphenylene orterphenylene. Particular units have the formula

[0073] where m is 1, 2 or 3. When the polymer is the product ofnucleophilic synthesis, such units may have been derived from one ormore dihalides, for example selected from 4,4′-dihalobenzophenone,4,4′bis(4-chlorophenylsulphonyl)biphenyl, 1,4,bis(4-halobenzoyl)benzeneand 4,4′-bis(4-halobenzoyl)biphenyl.

[0074] They may of course have been derived partly from thecorresponding bisphenols.

[0075] The polyaromatic may be the product of nucleophilic synthesisfrom halophenols and/or halothiophenols. In any nucleophilic synthesisthe halogen if chlorine or bromine may be activated by the presence of acopper catalyst.

[0076] Such activation is often unnecessary if the halogen is activatedby an electron withdrawing group. In any event fluoride is usually moreactive than chloride. Any nucleophilic synthesis of the polyaromatic iscarried out preferably in the presence of one or more alkali metalsalts, such as KOH, NaOH or K₂CO₃ in up to 10% molar excess over thestoichiometric.

[0077] As previously mentioned, said at least one polyaromatic containsreactive end groups. Reactive end groups may be obtained during thepreparation from monomers or by conversion from polymers havingnon-reactive end groups or having a different type of end groups.

[0078] The polyaromatic of the invention may be further combined withadditional polymers in reactive or non reactive manner, for examplepolyimides, polyolefins (polypropylene PP, polyphenyleneoxide PPO,polyvinylchloride PVC), acrylics, aromatic polyesters (polyethylteraphalate PET) or thermoplast or thermoset polymers as hereinbeforedescribed. For example the polyaromatic may be reacted with polyimide,semicrystalline PET/PEK, PEG or siloxane for enhanced Tg, solventresistance and the like.

[0079] Thermoset polymers may be selected from the group consisting ofan epoxy resin, an addition-polymerisation resin, especially abis-maleimide resin, a formaldehyde condensate resin, especially aformaldehyde-phenol resin, a cyanate resin, an isocyanate resin, aphenolic resin and mixtures of two or more thereof, and is preferably anepoxy resin derived from the mono or polyglycidyl derivative of one ormore of the group of compounds consisting of aromatic diamines, aromaticmonoprimary amines, aminophenols, polyhydric phenols, polyhydricalcohols, polycarboxylic acids and the like, or a mixture thereof, acyanate ester resin or a phenolic resin. Examples ofaddition-polymerisation resins are acrylics, vinyls, bis-maleimides, andunsaturated polyesters. Examples of formaldehyde condensate resins areurea, melamine and phenols.

[0080] Preferably the thermoset polymer comprises at least one epoxy,cyanate ester or phenolic resin precursor, which is liquid at ambienttemperature for example as disclosed in EP-A-0 311 349, EP-A-0 365 168,EPA 91310167.1 or in PCT/GB95/0 1303.

[0081] An epoxy resin may be selected from N,N,N′N′-tetraglycidyldiamino diphenylmethane (eg “MY 9663”, “MY 720” or “MY 721” sold byCiba-Geigy) viscosity 10-20 Pa s at 50° C.; (MY 721 is a lower viscosityversion of MY720 and is designed for higher use temperatures);N,N,N′,N′-tetraglycidyl-bis(4-aminophenyl)-1,4-diiso- propylbenzene (egEpon 1071 sold by Shell Chemical Co) viscosity 18-22 Poise at 110° C.;N,N,N′,N′-tetraglycidyl-bis(4-amino-3,5-dimethylphenyl)-1,4-diisopropylbenzene,(eg Epon 1072 sold by Shell Chemical Co) viscosity 30-40 Poise at 110°C.; triglycidyl ethers of p-aminophenol (eg “MY 0510” sold byCiba-Geigy), viscosity 0.55-0.85 Pa s at 25° C.; preferably of viscosity8-20 Pa at 25° C.; preferably this constitutes at least 25% of the epoxycomponents used; diglycidyl ethers of bisphenol A based materials suchas 2,2-bis(4,4′-dihydroxy phenyl) propane (eg “DE R 661” sold by Dow, or“Epikote 828” sold by Shell), and Novolak resins preferably of viscosity8-20 Pa s at 25° C.; glycidyl ethers of phenol Novolak resins (eg “DEN431” or “DEN 438” sold by Dow), varieties in the low viscosity class ofwhich are preferred in making compositions according to the invention;digylcidyl 1,2-phthalate, eg GLY CEL A-100; diglycidyl derivative ofdihydroxy diphenyl methane (Bisphenol F) (eg “PY 306” sold by CibaGeigy) which is in the low viscosity class. Other epoxy resin precursorsinclude cycloaliphatics such as3′,4′-epoxycyclohexyl-3,-4-epoxycyclohexane carboxylate (eg “CY 179”sold by Ciba Geigy) and those in the “Bakelite” range of Union CarbideCorporation.

[0082] A cyanate ester resin may be selected from one or more compoundsof the general formula NCOAr(Y_(x)Ar_(m))_(q)OCN and oligomers and/orpolycyanate esters and combinations thereof wherein Ar is a single orfused aromatic or substituted aromatics and combinations thereof andtherebetween nucleus linked in the ortho, meta and/or para position andx=0 up to 2 and m and q=0 to 5 independently. The Y is a linking unitselected from the group consisting of oxygen, carbonyl, sulphur, sulphuroxides, chemical bond, aromatic linked in ortho, meta and/or parapositions and CR₁R₂ wherein R₁ and R₂ are hydrogen, halogenated alkanes,such as the fluorinated alkanes and/or substituted aromatics and/orhydrocarbon units wherein said hydrocarbon units are singularly ormultiply linked and consist of up to 20 carbon atoms for each R₁ and/orR₂ and P(R₃R₄R′₄R₅) wherein R₃ is alkyl, aryl, alkoxy or hydroxy, R′₄may be equal to R₄ and is a singly linked oxygen or chemical bond, R₅ isdoubly linked oxygen or chemical bond and Si(R₃R₄R′₄R₆) wherein R₃ andR₄, R′₄ are defined as in P(R₃R₄R′₄R₅) above and R₅ is defined similarto R₃ above. Optionally, the thermoset can consist essentially ofcyanate esters of phenol/formaldehyde derived Novolaks ordicyclopentadiene derivatives thereof, an example of which is XU71787sold by the Dow Chemical Company.

[0083] A phenolic resin may be selected from any aldehyde condensateresins derived from aldehydes such as methanal, ethanal, benzaldehyde orfurfuraldehyde and phenols such as phenol, cresols, dihydric phenols,chlorphenols and C₁₋₉ alkyl phenols, such as phenol, 3- and 4-cresol(1-methyl, 3- and 4-hydroxy benzene), catechol (2-hydroxy phenol),resorcinol (1,3-dihydroxy benzene) and quinot (1,4-dihydroxy benzene).Preferably phenolic resins comprise cresol and novolak phenols.

[0084] The thermoset polymer is suitably the product of at least partlycuring a resin precursor using a curing agent and optionally a catalyst.

[0085] The weight proportion of thermoplast component in the compositionis typically in the range 5 to 100%, preferably 5 to 90%, especially 5to 50, for example 5 to 40%.

[0086] The thermoset and polyarylaromatic are suitably reacted in thepresence of a curing agent to provide a resin composition. The curingagent is suitably selected from any known curing agents, for example asdisclosed in EP-A-0 311 349, EPA 91310167.1, EP-A-0 365 168 or inPCT/GB95/01303, which are incorporated herein by reference, such as anamino compound having a. molecular weight up to 500 per amino group, forexample an aromatic amine or a guanidine derivative. Particular examplesare 3,3′- and 4-,4′-diaminodiphenylsulphone, (available as “DDS” fromcommercial sources), methylenedianiline,bis(4-amino-3,5-dimethylphenyl)-1,4-diisopropylbenzene (available asEPON 1062 from Shell Chemical Co);bis(4-aminophenyl)-1,4-diisopropylbenzene (available as EPON 1061 fromShell Chemical Co); 4-chlorophenyl-N,N-dimethyl-urea, eg Monuron;3,4-dichlorophenyl-N,N-dimethyl-urea, eg Diuron and dicyanodiamide(available as “Amicure CG 1200 from Pacific Anchor Chemical). Otherstandard epoxy curing agents such as aliphatic diamines, amides,carboxylic acid anhydrides, carboxylic acids and phenols can be used ifdesired. If a novolak phenolic resin is used as the main thermosetcomponent a formaldehyde generator such as hexamethylenetetraamine (HMT)is typically used as a curing agent.

[0087] Conventionally, and as described in EP-A-0 311 349 or inPCT/GB95/01303, a catalyst for the epoxy resin component/curing agentreaction may also be used, typically a Lewis acid or a base.

[0088] In a further aspect there is provided according to the presentinvention a process for the preparation of a polymer compositioncomprising at least one aromatic polymer or a mixture thereof, theprocess comprising:

[0089] i) providing polyaromatic polymer chains having Mn in a firstrange as hereinbefore defined and characterised by a polymer flowtemperature, wherein the at least one polyaromatic polymer chains haveat least one reactive end group, and

[0090] ii) providing at least one chain linking component having atleast two linking sites as hereinbefore defined, and

[0091] iii) admixing at a first temperature which is less than the chainlinking temperature at which the reactive end group and linking sitesare adapted to react as hereinbefore defined.

[0092] The admixing may be carried out at or below the composition flowtemperature employed for shaping the composition, and shaping may becarried out simultaneously or subsequently.

[0093] The chain linking component may be prepared by interconversionfrom the corresponding component to introduce linking sites, or may beprepared by a dedicated synthesis.

[0094] In a further aspect of the invention there is therefore provideda process for the preparation of a chain linking component ashereinbefore defined by interconversion from the corresponding componentto introduce a plurality of linking sites.

[0095] The polymers of the composition may be prepared from polymerprecursors comprising monomers in the presence of a reactive componentadapted to provide the desired reactive end group, or may be prepared byinterconversion from the polymer having a different type of end group byreaction with a component adapted to provide the desired reactive endgroups. Processes for the preparation of polyaromatics are disclosed in“Polyaromatics”, P. T. McGrail, Polymer International 41(1996) 103-121as hereinbefore referred, the contents of which are incorporated hereinby reference.

[0096] In one preferred embodiment, the polymers are prepared frommonomers obtained and isolated with the use of first and second fluidsin the substantial absence of an effective amount of azeotrope,according to copending UK patent application number 9803714.6, thecontents of which are incorporated herein by reference.

[0097] It is of particular advantage that the process according to thisembodiment enables the preparation of polymers with convenient isolationthereof from by-products of the reaction, by precipitation from thereaction mixture. This has the advantage that the polymer may beprepared in a relatively low number average molecular weight in a firstrange as hereinbefore defined, without incurring problems inpurification thereof, or loss of yield on isolation.

[0098] In a particular advantage of the present invention, the monomerscan be prepared according to the abovementioned process in a preselectedMn and with desired end groups. As the monomers are in solution it ispossible to introduce alternative end groups by reaction in the solutionprior to isolation thereof to form polymer chains of a compositionaccording to the present invention.

[0099] In fact the use of the abovementioned preferred process inobtaining polymer compositions having a number average molecular weightin a first range for impregnation, molding or shaping which issubstantially less than that which has been commonly employed in the artpreviously, enables the preparation in excellent manner of impregnated,molded or shaped articles of excellent quality.

[0100] The first fluid suitably comprises at least one dipolar aproticsolvent, optionally present in a fluid mixture with other liquids or nonliquids, which acts to promote the polymerisation reaction, preferablyselected from one or more of sulphur oxides, such as sulphoxides andsulphones, formamides, pyrrolidones, cyclic ketones and the like.

[0101] Preferably the second fluid is any fluid displaying the requiredsolvent properties, for example is selected from alcohols anddemineralised water or demineralised aqueous solvents and mixturesthereof.

[0102] The relative amounts of monomer precursors may be selectedaccording to the desired polymer composition. A composition comprisingpolyethersulphones to polyetherethersulphones in a desired ratio maytherefore be obtained by employing respective proportions of bisphenoland dihalides to monophenol in the same molar amounts. Preferably theproportion of bisphenol and dihalide to monophenol is in the range of10:90-100:0, preferably 30:70-70:30, providing the polyarylsulphonehaving PES:PEES of the same proportions.

[0103] Preferably reactive end groups are introduced at the outset withthe polymer precursors. This has the advantage of avoiding the need toopen up the reactor at a later quenching stage, which risks disturbingthe reaction and introducing gaseous contaminants such as oxygen and thelike. Moreover without being limited to this theory it is thought thatthe presence of reactive end groups throughout the process may lead tocontrolled and stable polymer chain growth which is as a result of selfregulation of chain length. Such self regulation may take the form ofcontinuous growth of chains with simultaneous chain scission.

[0104] Alternatively reactive end groups may be added in a furtheramount of first fluid to the reacted polymer precursors at a furtherelevated temperature for a further period. This has the advantage ofquenching the reaction mixture to halt the further development ofmolecular weight.

[0105] Reactive end groups may be the same as or different to a polymerprecursor as hereinbefore defined. End groups comprising halo or hydroxyreactive groups may be obtained by addition of an excess of a componentas hereinbefore defined providing the repeating units of thepolyarylsulphone, for example employing a slight molar excess of thedihalide or the bisphenol and monophenol. This has the advantage ofconvenience and accuracy of handling the minimum number of components.Alternatively end groups comprising amino reactive groups may beobtained by addition of a pre-determined amount of a monomer, which doesnot provide repeating units of the polyarylsulphone, for example ofaminophenol. This has the advantage of dedicated control of end groupstoichiometry and molecular weight development. The composition may beisolated in the form of a solid phase precipitate which may be purifiedand dried as hereinbefore defined and according to known techniques. Theprecipitate may be further processed to a useable physical form, forexample extruded into pellets, drawn or spun as fibres or films and thelike, in particular as disclosed in copending GB 0020630 the contents ofwhich are incorporated herein by reference.

[0106] The polymer chains obtained may be further converted toderivatives or analogues of the polyaromatic by reaction with a suitablefunctionalising or derivatising agent. For example the end groups may bemodified by providing the polymer chains in the reaction solution, orpost-isolation, in a solution of a suitable solvent together with anyfunctionalising or derivatising agent according to known techniques.

[0107] In a further aspect of the invention there is provided a processfor providing a composition as hereinbefore defined as a shaped articleor film, such as impregnated, moulded, injection moulded, extruded orthe like articles or cast, spayed or rollered films, comprisingobtaining the composition according to the invention as hereinbeforedefined, subjecting to a first temperature as hereinbefore definedcorresponding to the flow temperature of the unreacted composition andshaping according to known techniques, optionally in solution of asuitable solvent, subjecting to a second elevated temperature ashereinbefore defined corresponding to the temperature for chain linkingreaction of the composition and obtaining a shaped article or filmhaving increased number average molecular weight in a second range ashereinbefore defined.

[0108] In the case that the composition is provided as fibre or film, apre-form shape may be provided at ambient temperature, for example byweaving, or comingling fibres and the like, predisposed to flow into adesired shape by melting or dissolving at flow temperature.

[0109] Preferably processing conditions comprise elevated temperature inthe range of 150-400° C. more preferably 175-300° C., for example190-250° C. Processing conditions may comprise atmospheric or elevatedtemperature adapted to the reaction temperature as hereinbefore definedby gradual or ramp increase from the flow temperature. It is aparticular advantage that processing may be conducted at atmosphericpressure.

[0110] In a further aspect there is provided according to the inventiona resin formulation comprising polyaromatic polymer chains and a chainlinking component as hereinbefore defined.

[0111] A resin composition is particularly suitable for fabrication ofstructures, including load-bearing or impact resisting structures. Forthis purpose it may contain a reinforcing agent such as fibres. Fibrescan be added short or chopped typically of mean fibre length not morethan 2 cm, for example about 6 mm. Alternatively, and preferably, thefibres are continuous and may, for example, be unidirectionally-disposedfibres or a woven fabric, ie the composite material comprises a prepreg.Combinations of both short and/or chopped fibres and continuous fibresmay be utilised. The fibres may be sized or unsized. Fibres can be addedtypically at a concentration of 5 to 35, preferably at least 20%, byweight. For structural applications, it is preferred to use continuousfibre for example glass or carbon, especially at 30 to 70, moreespecially 50 to 70% by volume.

[0112] The fibre can be organic, especially of stiff polymers such aspoly paraphenylene terephthalamide, or inorganic. Among inorganic fibresglass fibres such as “E” or “S” can be used, or alumina, zirconia,silicon carbide, other compound ceramics or metals. A very suitablereinforcing fibre is carbon, especially as graphite. Graphite fibreswhich have been found to be especially useful in the invention are thosesupplied by Amoco under the trade designations T650-35, T650-42 andT300; those supplied by Toray under the trade designation T800-HB; andthose supplied by Hercules under the trade designations AS4, AU4, IM 8and IM 7.

[0113] Organic or carbon fibre is preferably unsized or is sized with amaterial that is compatible with the composition according to theinvention, in the sense of being soluble in the liquid precursorcomposition without adverse reaction or of bonding both to the fibre andto the thermoset/thermoplastic composition according to the invention.In particular carbon or graphite fibres that are unsized or are sizedwith epoxy resin precursor or thermoplast such as polyarylsulphone arepreferred. Inorganic fibre preferably is sized with a material thatbonds both to the fibre and to the polymer composition; examples are theorgano-silane coupling agents applied to glass fibre.

[0114] The composition may contain for example conventional tougheningagents such as liquid rubbers having reactive groups, aggregates such asglass beads, rubber particles and rubber-coated glass beads, filler suchas polytetrafluorethylene, silica, graphite, boron nitride, mica, talcand vermiculite, pigments, nucleating agents, and stabilisers such asphosphates. The total of such materials and any fibrous reinforcingagent in the composition should be at least 20% by volume, as apercentage of the total volume of the polysulphone/thermoset mixture.The percentages of fibres and such other materials are calculated on thetotal composition after reaction or processing at the hereinbelowdefined temperatures.

[0115] Preferably the composition is obtained as hereinbefore defined,by mixing the polyaromatic, chain linking component, thermoset precursorand (at some stage) any fibrous reinforcing agent and other materials. Asolvent may be present. The solvent and the proportion thereof arechosen so that the mixture of polymer and resin precursor form at leasta stable emulsion, preferably a stable apparently single-phase solution.The ratio of solvent to polyaromatic is suitably in the range 5:1 to20:1 by weight. Preferably a mixture of solvents is used, for example ofa halogenated hydrocarbon and an alcohol, in a ratio suitably in therange 99:1 to 85:15. Conveniently the solvents in such a mixture shouldboil at under 100° C. at 1 atm pressure and should be mutually misciblein the proportions used.

[0116] Preferably however a solvent is not present and the polyaromatic,chain linking component and thermoset or precursor are brought togetherat Mn in a first range avoiding the need for hot melting and/or highshear mixing.

[0117] The mixture is stirred until sufficiently homogeneous. Thereafterany solvent is removed by evaporation to give a resin composition.Evaporation is suitably at 50-200° C. and, at least in its final stages,can be at subatmospheric pressure, for example in the range 13.33 Pa to1333 Pa (0.1 to 10 mm Hg). The resin composition preferably contains upto 5% w/w of volatile solvent, to assist flow when used to impregnatefibres. This residual solvent will be removed in contact with the hotrollers of the impregnating machine.

[0118] Suitably the composition in form of a resin solution istransferred onto a suitable mould or tool for preparation of a panel,prepreg or the like, the mould or tool having been preheated to adesired degassing temperature.

[0119] The stable emulsion is combined with any reinforcing, toughening,filling, nucleating materials or agents or the like, and the temperatureis raised to initiate flow and processing thereof. Suitably processingis carried out at elevated temperature up to 150° C., preferably in therange of 100° C. to 130° C., more preferably at about 120° C.-125° C.,and with use of elevated pressure to restrain deforming effects ofescaping gases, or to restrain void formation, suitably at pressure ofup to 10 bar, preferably in the range of 3 to 7 bar abs. Suitably theprocessing temperature is attained by heating at up to 5° C./min, forexample 2° C. to 3° C./min and is maintained for the required period ofup to 9 hours, preferably up to 6 hours, for example 3 to 4 hours.Pressure is released throughout and temperature reduced by cooling at upto 5° C./min, for example up to 3° C./min.

[0120] It is an advantage that second stage processing is not requiredto raise the glass transition temperature of the product or otherwise.This is in view of the fact that the Tg is a function of the originalpolymer architecture. Tg may be increased by incorporation of functionallinking components.

[0121] The resin composition, possibly containing some volatile solventalready present or newly added, can be used for example as an adhesiveor for coating surfaces or for making solid structures by castingpossibly in a foamed state. Short fibre reinforcement may beincorporated with composition prior to curing thereof. Preferably afibre-reinforced composition is made by passing essentially continuousfibre into contact with such resin composition. The resultingimpregnated fibrous reinforcing agent may be used alone or together withother materials, for example a further quantity of the same or adifferent polymer or resin precursor or mixture, to form a shapedarticle. This technique is described in more detail in EP-A-56703,102158 and 102159.

[0122] A further procedure comprises forming composition into film byfor example compression moulding, extrusion, melt-casting orbelt-casting, laminating such films to fibrous reinforcing agent in theform of for example a non-woven mat of relatively short fibres, a wovencloth or essentially continuous fibre in conditions of temperature andpressure sufficient to cause the mixture to flow and impregnate thefibres and subsequently processing the resulting laminate.

[0123] The resulting multi-ply laminate may be anisotropic in which thefibres are continuous and unidirectional, orientated essentiallyparallel to one another, or quasi-isotropic in each ply of which thefibres are orientated at an angle, conveniently 45° as in mostquasi-isotropic laminates but possibly for example 30° or 60° or 90° orintermediately, to those in the plies above and below. Orientationsintermediate between anisotropic and quasi-isotropic, and combinationlaminates, may be used. Suitable laminates contain at least 4 preferablyat least 8, plies. The number of plies is dependent on the applicationfor the laminate, for example the strength required, and laminatescontaining 32 or even more, for example several hundred, plies may bedesirable. There may be aggregates, as mentioned above in interlaminarregions. Woven fabrics are an example of quasi-isotropic or intermediatebetween anisotropic and quasi-isotropic.

[0124] In a further aspect of the invention there is provided the use ofa composite mould or tool, bagging material, and the like conventionallyused for thermoset materials, to contain or support a compositionaccording to the invention as hereinbefore defined during the processingthereof. Preferably these are constructed of any suitable unsaturatedpolyester or thermoset resin such as bis-maleimides, nylon film and thelike having a heat resistance in excess of the processing temperature tobe employed.

[0125] In a further aspect of the invention there is provided a prepregcomprising a composition as hereinbefore defined and continuous fibres,obtained by a process as hereinbefore defined.

[0126] In a further aspect of the invention there is provided acomposite comprising pre-pregs as hereinbefore defined laminatedtogether by heat and pressure, for example by autoclave, compressionmoulding, or by heated rollers, at a temperature above the curingtemperature of the polymer composition.

[0127] In a further aspect of the invention there is provided athermoplast or a thermoplast-modified thermoset resin shaped productcomprising a composition, pre-preg or laminar composite as hereinbeforedefined, which is obtained by the method as hereinbefore defined.Preferably such product is for use in transport such as aerospace,aeronautical, marine or automotive industries, rail and coach industriesor in building/construction industry, or for use in non-high performancetransport applications, non-construction applications and adhesiveapplications, including high temperature adhesive applications.

[0128] The invention is now illustrated in non limiting manner withreference to the following examples.

EXAMPLE 1

[0129] Synthesis of 40:60 PES:PEES Copolymer, Hydroxy Terminated andCalculated to Have a Molecular Weight of 7,000

[0130] Bisphenol-S (18.92 gms), Dichlorodiphenylsulphone (52.84 gms) andHydroquinone (12.49 gms) were charged to a 3 necked round bottomedflask. Sulpholane (194 mls) was added to the reactants. The reactionflask was then flushed with nitrogen. The reactants were stirred at RTwhilst Potassium Carbonate (27.60 gms) was added. After about 5 minutesheat was applied to the reactor using an oil bath set at 180° C. As thetemperature rose the reaction converting Hydroquinone and Bisphenol-S tobisphenates proceeded, water and carbon dioxide were produced. Thereaction was held at 180° C. for 30 minutes, and water was vented fromthe reactor. The temperature was raised again to 205° C. and held for afurther 60 minutes. Again during this period a large amount of water wasproduced. The temperature was raised again to 225° C. and the reactionwas completed with a hold time of 4 hours.

[0131] Upon completion of the reaction the polymer solution was cooledto less than 60° C. and the polymer was precipitated into stirringMethanol. The Sulpholane is extremely soluble in Methanol, it is alsoextremely soluble in water. The polymer was then filtered from themethanol and was then macerated, filtered again and washed several timeswith water and dilute Acetic Acid until the pH of the effluent wasneutral. The polymer was then dried at 100° C. overnight.

[0132] As the bisphenate forms it reacts with the DCDPS by displacingthe chlorine group producing an ether link and Potassium Chloride, as abyproduct. Bisphenate formation and the displacement of the chlorinegroups continues until all of the monomers have been consumed and nomore of the bisphenate remains. The resulting polymer is hydroxyterminated and is shown in FIG. 3 (I). Characterisation of this polymercan be seen in Table 4 found in the appendices.

EXAMPLE 2

[0133] Synthesis of 40:60 PES:PEES Copolymer, Amine Terminated,Calculated Molecular Weight 7000

[0134] Polymer was synthesised using the procedure described in Example1 and including m-aminophenol (1.75 gms) as monomer, utilisingSulpholane as the polymerisation solvent, and using calculated amount ofmonomers, such that the polymer was amine terminated. It was notpossible to get mechanical data for this due to the brittle nature ofthe polymer. The structure is shown in FIG. 1 (I).

EXAMPLE 3

[0135] Procedure for the Moulding of Chain Extended Thermoplastic NeatResin Panels

[0136] Amine Terminated 40:60 PES:PEES Copolymer Chain Extended withBenzophenone Tetracarboxylic Dianhydride (BTDA).

[0137] The low Mn amine ended polymer of Example 2 (100 g) ispredissolved in NMP (250 ml) at RT. Upon dissolution the relative amountof BTDA (8.63 g), required to endcap the amine groups (as characterisedin Table 4 of the appendices), is added and the blend is warmed to about50° C. After about 30 minutes further resin of Example 2 (50 g—ratio ofBTDA terminated resin to amine terminated resin was 2:1) is added to thesolution. This forms a blend of anhydride terminated polymer and amineterminated polymer (FIG. I-II and I-), in predetermined ratio, thesolution is then precipitate into methanol. The precipitated polymer isthen washed several times and dried at 100° C.

[0138] A 6″×4″×3 mm compression mould is then prewarmed to 300° C. asare the platens of a compression press. The polymer is then taken fromthe oven at 100° C. and added to the compression mould which is placedinto the press and the platens closed. A pressure of 1 ton is appliedinitially and allowed to reduce. This represents the melting and flowingof the polymer blend. After about 10 minutes pressure is applied againuntil small amounts of polymer flashing are seen coming from the mould.This pressure is then sustained for about 1 hour, the mould cooled to RTand pressure removed. The neat resin panel is removed. Visualexamination of the moulded neat resin part showed it to be transparentand completely intact. Flashings from the side of the panel weresubjected to a simple “crease” test which demonstrated its increasedtoughness over the polymer described in Example 2. This polymer couldnot be creased to form a “hinge” due to its brittle nature.

[0139] Measurements of flexural modulus, yield strength, fracturestrength and fracture toughness were made for different molar ratios ofpolymer to chain linking component. The results are shown in Table 1.

[0140] Gel Permeation Chromatography (GPC) was used to determine the Mn(number average molecular weight) and the Mw (weight average molecularweight) of the chain extended polymer and that of the polymer fromExample 2. The results are shown in FIG. 2, which demonstrate theconsiderable change in molecular weight distribution.

Comparative 1

[0141] Preparation of Polymer Composition Comprising 40:60 PES:PEESCopolymer, Chlorine Terminated, Calculated Molecular Weight 20,000 CuredInto Neat Resin Casting

[0142] The high molecular weight chlorine terminated polymer wassynthesised using Hydroquinone (g), Bisphenol-S (g) and DCDPS (g)Stoichiometry was such that the polymer was chlorine terminated. Theprocess for the polymerisation was carried out as described inExample 1. Characterisation of the polymer can be seen in Table 4 of theappendices.

[0143] Neat resin compression castings were obtained using the procedureas described in Example 3. Visual inspection of the moulded neat resinpanel showed it to be similar to that of the chain extended polymerdescribed under Example 3.

[0144] The mechanical properties were investigated. The results areshown in Table 1.

Comparative 2

[0145] Preparation of Commercially Available 3600P Polymer CompositionCured Into Neat Resin Casting

[0146] Commercially available 3600P was obtained and neat resin castingobtained using the procedure as described in Example 3.

[0147] The mechanical properties were investigated. The results areshown in Table 1. Characterisation of the polymer can be seen in Table 4of the appendices. TABLE 1 Mechanical properties of neat resins GlassAmine ended tran- Flexural Fracture PES:PEES/ sition mod- Yield Fracturetough- Exam- BTDA ended temp ulus strength strength ness ple PES:PEES (°C.) (GPa) (MPa) (MNm^(−3/2)) (KJm⁻²) 3 1/2 226 3.05 123.7 1.95 1.55 31/1.5 227 2.8 122.2 2.16 1.9 3 1/1.25 230 3.19 125.05 2.21 1.95 C2 3600PPES 225 2.8 100 2 2 C1 Chlorine 225 3 120 2.15 2.2 terminated PES:PEES

[0148] This table demonstrates that the chain linked materials produceidentical neat resin mechanical properties to that of their engineeringcommercial counterparts

EXAMPLE 4

[0149] Procedure for the Preparation of Prepreg and the Moulding ofChain Extended Thermoplastic Composite Panels

[0150] Amine Terminated 40:60 PES:PEES Copolymer Chain Extended withBenzophenone Tetracarboxylic Dianhydride (BTDA).

[0151] The low Mn amine ended polymer (500 g) is predissolved in NMP(500 ml), at RT. Upon dissolution the relative amount of BTDA (43.15 g),required to endcap the amine groups, is added and the blend is warmed toabout 50° C.

[0152] After about 30 minutes further resin of Example 2 (250 g) isadded to the solution. This forms a blend of anhydride terminatedpolymer and amine terminated polymer (FIG. 1-II & I), in predeterminedration.

[0153] The polymer solution at an appropriate solids level is then usedfor the solution impregnation of carbon fibre. In order to aid thewetting of the carbon fibres the temperature of the impregnation bathwas kept at 100° C. This is considerably less than the temperaturerequired to impregnate conventional high molecular weight thermoplasticswhich are typically in the area of 400° C. The fibre/resin/solventmixture is then passed over a series of heated rollers ranging intemperature from 150 to 220° C. This is required to remove the NMPsolvent. The quality of the prepreg was excellent and showed goodconsolidation of the fibre tows in the thermoplastic matrix. The solventfree prepreg can then be used to prepare composite panels.

[0154] A 6″×4″×3 mm open cast mould is filled with a number of layers ofprepreg to prepare a defined configuration for a particular mechanicaltest. The mould is then placed into a vacuum bagging system, typical ofthe art, and placed into a pressclave or autoclave. Vacuum is applied,to consolidate the prepreg layers and the pressclave is then heated at apredetermined rate to 300° C. as the vacuum is removed. A suitableprocessing cycle is then followed after which the cooled panel cooled atpredetermined cooling rate is removed. Quality assurance testing wascarried out to establish the consolidation of the composite in terms ofvoid content by sectioning and micrographic observation. The fibrevolume was established using acid etching. The fibre volume was found tobe 65% and the void content was acceptable.

[0155] Measurements of transflexural strength and short beam shear weremade for different molar rations of polymer chain to chain linkingcomponent. The results are shown in Table 2 and FIG. 1.

Comparative 3

[0156] Preparation of Prepreg of Commercially Available 5200P

[0157] Commercially available 5200P (a polyethersulphone manufactured byVictrex), characterisation of this polymer can be seen in Table 4 of theappendices, was impregnated onto carbon fibres (AS4) using the solutionimpregnation route described in Comparative 2, except in this case theNMP impregnation solution had to be kept at 175° C., in order to renderthe solution viscosity low enough for impregnation purposes.

[0158] The quality of the resulting prepreg was inferior to that of thematerial from Comparative 2 in that consolidation of the fibre towswithin the thermoplastic matrix was low resulting in fibre tows breakingaway from the unidirectional prepreg.

[0159] This polymer was also melt impregnated at 400° C. from a solidsolvent, diphenylsulphone (DPS), typical of the art as described in USpatent no. 5374694 (EP 0 412 827 B)

[0160] Both prepregs were then used to prepare composite laminates forthe determination of Short Beam Shear (SBS) and Transflexural Strength(TFS) the results of which can be seen in Table 2.

Comparative 4

[0161] Preparation of Prepreg of Commercially Available 3600P

[0162] Commercially available 3600P (a polyethersulphone manufactured byVictrex), characterisation of this polymer can be seen in Table 4 of theappendices, was impregnated onto carbon fibres (AS4) using the solutionimpregnation route described in Comparative 2, except in this case theNMP impregnation solution had to be kept at 175° C., in order to renderthe solution viscosity low enough for impregnation purposes.

[0163] The quality of the resulting prepreg was inferior to that of thematerial from Comparative 2 in that consolidation of the fibre towswithin the thermoplastic matrix was low resulting in fibre tows breakingaway from the uni-directional prepreg.

[0164] This polymer was also melt impregnated at 400° C. from a solidsolvent, diphenylsulphone (DPS), typical of the art as described inpatent no. Both prepregs were then used to prepare composite laminatesfor the determination of Short Beam Shear (SBS) and TransflexuralStrength (TFS) the results of which can be seen in Table 2. TABLE 2Mechanical properties (transflexural strength (TFS) and short beam shear(SBS)) of prepregs Example Material (molar ratio) TFS (MPa) SBS (MPa) 4PES:PEES 24.6 70 4 Amine ended PES:PEES: 54.9 78 anhydride endedPES:PEES (1:2) 4 Amine ended PES:PEES: 98.2 83 anhydride ended PES:PEES(1:1.5) 4 Amine ended PES:PEES: 127.2 85 anhydride ended PES:PEES(1:1.25) C3 5200P (solution) 55 75 C3 5200 (melt) 95 69 C4 3600P(solution) 48 72 C4 3600 (melt) 94 87

EXAMPLE 5

[0165] Preparation of Diamine Ended PEK

[0166] 4,4′-fluorobenzophenone (27.51 g), 4,4′hydroxy benzophenone(21.41 g), m-aminophenol (6.68 g) and potassium carbonate (18.32 g) werereacted in diphenyl sulphone (147 g) to give a 1.5K amine terminated PEKpolymer the characterisation results of which can be seen in Table 4 ofthe appendices. The reaction took several stages to complete from thepreparation of the potassium salts of m-aminophenol and4′-hydroxybenzophenone to the final polymerisation stage.

[0167] The polymer was isolated into acetone and characterised using¹Hnmr and DSC, confirming that the polymer backbone was PEK and that theend groups were >95% amine. DSC analysis showed a single melting pointsequence, a Tp at 353° C. The product structure is shown in FIG. 4 (II).

[0168] The level of crystallinity was measured using X-ray diffraction(XRD) and Differential Scanning Calorimetry (DSC) and was found to be inthe range of 50-60%.

EXAMPLE 6

[0169] Preparation of APA/PEK Multiblocks

[0170] The anhydride ended APA of Example 3A., shown in FIG. 4(I) wasblended with the amine ended PEK of Example 5 (Mn 1500) in NMP—the amineterminated PEK was extremely soluble in the APA/NMP mixture and this wasunexpected—and on dissolution the blended polymer was precipitated intomethanol and the purified blend recovered.

[0171] The multiblock was prepared by heating the blend up to 310° C. ina compression press for 60 minutes prior to the application of pressureto press a thin film. The film was cooled to rt using air and waterblown through the platens of the press.

[0172] The film was very opaque, indicating its crystalline nature, andcharacterisation was by DSC. APA Mn was 10,000 and PEK Mn 1500. The DSCshowed a Tg of the multiblock occurring at 216° C., Tp at 369° C. with alevel of crystallinity of 12%. The product comprised repeating units asshown in FIG. 4 in the form of a multiblock.

EXAMPLE 7

[0173] Chain Linking of Crystalline Diamine Ended PEK PolymerComposition and Neat Resin Casting

[0174] An impregnation solution was prepared by synthesising theanhydride ended s APA (63 g), using the polymer characterised fromExample 3 and found in Table 4, in NMP at 50° C. using a stoichiometricamount of BTDA as described in Example 3. The previously synthesisedamine ended PEK (7 g), characterisation of this polymer can be found inTable 4 of the appendices, was then added and allowed to dissolve. Ondissolution the solution containing 40% solids was used to impregnateAS4 carbon fibre tows. The same conditions described earlier toimpregnate the chain extended system were utilised. Excellent lookingprepreg was produced having a fibre content of 64+/−2%. The productcomprised repeating units as shown in FIG. 4, having a constant valuefor a and b—small amounts of the polymer flashings were used tocharacterise the molecular weight of the chain extended polymer, theresults of which can be seen in Table 4.

[0175] TEM micrographs (FIGS. 5 and 6) show the morphology of theamorphous crystalline phases of the resin casting of Example 7. FIG. 5at low magnification (13.8K) shows a range of crystalline phasesrevealing various sizes and shapes. The lack of contrast around theinterface between amorphous and crystalline suggest a good interfacebetween the two phases. Further increased magnification in FIG. 6reveals a very well defined lamella structure.

EXAMPLE 8

[0176] Preparation of Sample of Amorphous Amine Ended KM Polymer Prepregof Example 4 of the Invention—For the Assessment of the InterlaminarShear Strength (ILSS) Properties

[0177] ILSS sample was prepared from the prepreg of Example 4, using thefollowing procedure.

[0178] Prepreg was moulded in an autoclave into panels with appropriatelay-up using a standard vacuum bag technique and the following curecycle:

[0179] heat to 125° C. at 2° C./min under pressure between 3 and 7 barabs;

[0180] hold 6 h while venting vacuum bag;

[0181] cool to rt at less than 3° C./min.

EXAMPLE 9

[0182] Preparation of Sample of Semicrystalline Amine Ended KM PEKPolymer Prepreg of Example 6 of the Invention—For the Assessment of theInterlaminar Shear Strength (ILSS) Properties

[0183] ILSS sample was prepared from the prepreg of Example 7, using theprocedure of Example 8.

Comparative 5

[0184] Preparation of Sample of HTA/IM6, Chlorine Ended—For theAssessment of the Interlaminar Shear Strength (ILSS) Properties

[0185] Interlaminar sample was prepared from a commercially availablechlorine ended Victrex polymer prepreg, using the procedure of Example8.

Comparative 6

[0186] Preparation of Sample of Low Mn HTA/MLW/IM6 Chlorine Ended—Forthe Assessment of the Interlaminar Shear Strength (ILSS) Properties

[0187] ILSS sample was prepared from a commercially available low Mnchlorine ended Victrex polymer prepreg, using the procedure of Example8.

EXAMPLE 10

[0188] Solvent Resistance as Determined by the % Retention of ILSSProperties of Processed Samples of the Invention

[0189] ILSS samples of the compositions of the invention obtained inExamples 8 and 9 and Comparative 5 and 6 were exposed to solvents and %retention of ILSS properties were determined.

[0190] The results are shown in Table 3 TABLE 3 % Solvent Resistance ofinterlaminar samples Solvent T/time C5 C6 8 9 MEK RT/1 hr 81% 0% 66% 77%JP8 RT/1000 hr 96% 60% 99% 85% JP8 70° C./1000 hr 76% 54% 82% 65%Skydrol RT/1000 hr 36% 30% 36% 77% Skydrol 70° C./1000 hr 28% 18% 22%44%

[0191] From the results the sample of Examples 8 and 9 comprisingamorphous and semi-crystalline block copolymer showed excellentproperties in the Skydrol exposure test at room temperature for 1000hours.

EXAMPLE 11

[0192] Tan Delta Measurements for Resins of Similar Mn

[0193] Rheology of samples of 9KPES, 9K PES:PEES and 9K amorphous HTAwere carried out using an RDS800 machine, all the polymers were hydroxylterminated and the characterisation of these polymers can be seen inTable 4 of the appendices. The polymers were melted between 40 mmdiameter plates and the materials elastic and storage moduli, viscosityand tan delta values, as a function of temperature, were determined. Thevalue of tan delta, which measures the separation between the twomoduli, is an indication of the flow properties of the polymer. Maximumseparation, that is elastic moduli lying below the storage moduli wouldrepresent a polymer with high flow properties. The results are shown inFIG. 7.

[0194] 9000 HTA is very inflexible and has flow temperature of 340° C.

[0195] 9000PES has flow temperature of 300° C.

[0196] 9000PES:PEES has flow temperature of 270° C., coincident with thechain linking reaction.

[0197] The polymer thus starts to react while flowing and continues toreact, to give product having Mn in the second range determined by themobility of the polymer. A highly mobile polymer will have a shortreaction window and result in low Mn (second range) polymer, compared toa less mobile polymer which has a long window of chain linking reactionand results in high Mn (second range) polymer.

EXAMPLE 12

[0198] Tan Delta Measurements for Resins of Different Mn

[0199] The measurements of Example 11 were repeated for 40:60 PES:PEESresins, amine ended, having different Mn. The results are shown in FIG.8. FIG. 9 shows a plot of the maximum tan delta against Mn as a linearrelation. Viscosity measurements (FIG. 10) are also shown to be regularfor low Mn resins of the invention, compared with the conventionalComparative 2.

EXAMPLE 13

[0200] Crystallinity Measurement

[0201] Comparison was made of multiblock PES:PEES compositions havingdifferent Mn, in terms of their crystallinity. The results indicatedthat crystallinity varies with Mn and can be as high as 25%. It was notpossible to significantly affect crystallinity by subjecting to elevatedtemperature.

[0202] The TEM shows crystalline phases of ordered stacked chains.

[0203] Further advantages of the invention are apparent from theforegoing.

1. A polymer composition comprising chains of at least one aromaticpolymer or a mixture thereof together with at least one chain linkingcomponent wherein the at least one aromatic polymer comprises polymerchains of number average molecular weight (Mn) in a first range andcharacterised by a polymer flow temperature, and having at least onereactive end group, and wherein the at least one chain linking componentcomprises at least two linking sites, characterised in that a pluralityof the polymer chain end groups are adapted to react with the linkingsites at chain linking temperature in excess of the polymer flowtemperature to form linked polymer chains of number average molecularweight (Mn) in a second range which is in excess of the first range,substantially thermoplastic in nature.
 2. A polymer composition asclaimed in claim 1 in the form of a precursor composition comprising anamount of at least one aromatic polymer as hereinbefore defined,together with an amount thereof, which has been prereacted at chainterminating conditions with the at least one chain linking component ashereinbefore defined to form polymer chains of Mn in the first range,characterised by a polymer flow temperature and having its reactive endgroups terminated with linking component, characterised in that aplurality of the polymer chain reactive end groups are adapted to reactwith the linking sites of linking component terminated polymer chains atchain linking temperature in excess of the polymer flow temperature toform linked polymer chains of number average molecular weight (Mn) in asecond range which is in excess of the first range.
 3. A polymercomposition as claimed in any of claims 1 & 2 wherein flow temperatureis the temperature at which the polymer attains a suitably molten orfluid state to enable a degree of polymer chain mobility to orient oralign itself for reaction.
 4. A polymer composition as claimed in any ofclaims 1 to 3 wherein the chain linking temperature is higher than aproduct processing temperature, to remove solvent and improve wet out ofthe prepreg.
 5. A polymer composition as claimed in any of claims 1 to 4wherein the number average molecular weight of the polyaromatic in thesecond range is in the range 9000 to 60000, for example 11000 to 25000,and in the first range is in the range of 2000 to 11000, for example inthe range of 3000 to
 9000. 6. A polymer composition as claimed in any ofclaims 1 to 5 which comprises a first and second polymers having thesame polymer backbone but different end groups, both being amorphous; orcomprises a first aromatic polymer having a lower flow temperature thana second similar aromatic polymer, both being amorphous the secondpolymer being rendered in flowable form in the presence of the firstpolymer in fluid form, thereby providing a processing aid; or comprisesan amorphous polymer and a crystalline or semi crystalline polymerhaving a characteristic melting point, the semi crystalline polymerbeing rendered flowable by solvent effect of the first polymer, actingas a cosolvent, diluent, dispersant, carrier or the like for the secondaromatic polymer.
 7. A polymer composition as claimed in any of claims 1to 6 wherein Reactive end groups (Y) and chain linking sites (Z) areselected from any functional groups providing active hydrogen and anypolar functional group adapted to react at elevated temperature in thepresence of an electrophile, preferably selected from active H, OH, NH₂,NHR or SH wherein R is a hydrocarbon group containing up to 8 carbonatoms, epoxy, (meth)acrylate, iso)cyanate, isocyanate ester, acetyleneor ethylene as in vinyl or allyl, maleimide, anhydride, carboxylic acid,oxazoline and monomers containing unsaturation; preferably reactive endgroups Y are selected from active H, OH, NH₂, NHR or SH and chainlinking sites Z are selected from epoxy, (meth)acrylate, (iso)cyanate,isocyanate ester, acetylene or ethylene as in vinyl or allyl, maleimide,anhydride, carboxylic acid, oxazoline and monomers containingunsaturation.
 8. A polymer composition as claimed in any of claims 1 to7 wherein a chain linking component is of the formula B(Z)n(Z′)n′wherein B is a polymer chain or is a carbon atom backbone having from 1to 10 carbon atoms, more preferably is an oligomer or polymer or is analiphatic, alicyclic or aromatic hydrocarbon optionally substitutedand/or including heteroatoms N,S,O or is a single bond or nucleus suchas C, O, S, N or Transition metal; Z and Z′ are each independentlyselected from functional groups as hereinbefore defined for Z; n and n′are each zero or a whole number integer selected from 1 to 6; and thesum of n and n′ is at least 2, preferably 2 to 10,000, more preferably 2to 10 or 10 to 500 or 500 to
 10000. 9. A polymer composition as claimedin any of claims 1 to 8 wherein a chain linking component comprises acompound of formula B(Z)nwherein B and Z are as hereinbefore defined inclaim 8 and n is selected from 2 to
 6. 10. A polymer composition asclaimed in and of claims 1 to 9 wherein a linear or branched polymerchain having at least two ends comprises at least two reactive endgroups and comprises a diol, polyol, diamine, polyamine, dithiol orpolythiol or the like and a chain linking component comprises at leasttwo linking sites whereby at least two polymer chains may be linkedtogether, and comprises a diepoxy, polyepoxy, di(meth)acrylate,poly(meth)acrylate, di(iso)cyanate, poly(iso)cyanate, diacetylene,polyacetylene, dianhydride, polyanhydride, dioxazoline, polyoxazoline.11. A polymer composition as claimed in any of claims 1 to 10 whereinlinking components are selected from the structures:

Benzophenone tetra carboxylic acid dianhydride (BTDA)

Maleic anhydride having units


12. A polymer composition as claimed in any of claims 1 to 11 wherein apolymer chain reactive end group is hydroxy and corresponds to a linkingsite functionality which is epoxy, whereby reaction thereof produces a βhydroxy ether linkage in polymers of increased number average molecularweight having either hydroxy or epoxy end groups as desired; or thereactive end group is NH₂ and the linking site functionality isanhydride, whereby reaction thereof produces an imide linkage inpolymers of increased number average molecular weight having NH₂ oranhydride end groups; or the reactive end group is NH₂ and the linkingsite functionality is maleimide.
 13. A polymer composition as claimed inany of claims 1 to 12 wherein the reactive end groups and linking sitesare present, calculated by the amount of polymer chain and linkingcomponent, in the required stoichiometric amounts to enable up to 100%linking of polymer chains in multiples of two (binary linking), three(tertiary linking), four (ternary linking), for example in a “star”architecture, and combinations thereof.
 14. A polymer composition asclaimed in any of claims 1 to 13 wherein an amount of additional intraor inter chain functionality is provided in the form of functionalgroups along the chain length whereby the chain linking component isselected to provide such functionality, selected from solvent resistance(F), cross-linking grafting sites (unsaturated groups), Tg enhancing orcompatibilising agents eg a microstructure compatible and reactive withanother polymer.
 15. A polymer composition as claimed in any of claims 1to 14 wherein the at least one polyaromatic comprises ether-linkedand/or thioether-linked repeating units, the units being selected fromthe group consisting of —(PhAPh)_(n)— and optionally additionally—(Ph)_(a)—wherein A is SO₂ or CO, Ph is phenylene, n=1 to 2, a=1 to 4and when a exceeds 1, said phenylenes are linked linearly through asingle chemical bond or a divalent group other than —A— or are fusedtogether directly or via a cyclic moiety such as a cycloalkyl group, a(hetero) aromatic group, or cyclic ketone, amide, amine, or imine, saidat least one polyarylsulphone having reactive pendant and/or end groups.16. A polymer composition as claimed in any of claims 1 to 15 whereinthe at least one polyaromatic comprises at least one polyaryl sulphonecomprising ether-linked repeating units, optionally additionallycomprising thioether-linked repeating units, the units being selectedfrom the group consisting of —(PhSO₂Ph)_(n)— and optionally additionally—(Ph)_(a)— wherein Ph is phenylene, n=1 to 2, a=1 to 3 and when aexceeds 1, said phenylenes are linked linearly through a single chemicalbond or a divalent group other than —SO₂— or are fused together,provided that the repeating unit —(PhSO₂Ph)_(n)— is always present insaid at least one polyarylsulphone in such a proportion that on averageat least two of said units —(PhSO₂Ph)_(n)— are in sequence in eachpolymer chain present, said at least one polyarylsulphone havingreactive pendant and/or end groups.
 17. A polymer composition as claimedin any of claims 1 to 16 wherein the polyaromatic comprises polyethersulphone, more preferably a combination of polyether sulphone andpolyether ether sulphone linked repeating units, in which the phenylenegroup is meta- or para- and is preferably para and wherein thephenylenes are linked linearly through a single chemical bond or adivalent group other than sulphone, or are fused together.
 18. A polymercomposition as claimed in claims 16 and 17 wherein the units are: I X PhSO₂ Ph X Ph SO₂ Ph (“PES”) and II X (Ph)a X Ph SO₂ Ph (“PEES”) where Xis 0 or S and may differ from unit to unit; the ratio is I to II(respectively) preferably between 10:90 and 80:20 such as between 35:65and 65:35.
 19. A polymer composition as claimed in claims 16 to 18wherein relative is proportions of the repeating units of thepolyarylsulphone expressed in terms of the weight percent SO₂ content,defined as 100 times (weight of SO₂)/(weight of average repeat unit) isat least 22, preferably 23 to 25%. When a=1 this corresponds to PES/PEESratio of at least 20:80, preferably in the range 35:65 to 65:35.
 20. Apolymer composition as claimed in claims 1 to 19 additionally comprisinga thermoset polymer component selected from the group consisting of anepoxy resin, an addition-polymerisation resin, especially abis-maleimide resin, a formaldehyde condensate resin, especially aformaldehyde-phenol resin, a cyanate resin, an isocyanate resin, aphenolic resin and mixtures of two or more thereof.
 21. A polymercomposition as claimed in claim 20 wherein the weight proportion ofthermoplast component in the composition is typically in the range 5 to100%, preferably 5 to 90%, especially 5 to 50, for example 5 to 40%. 22.A process for the preparation of a polymer composition comprising atleast one aromatic polymer or a mixture thereof, the process comprising:i) providing polyaromatic polymer chains having Mn in a first range ashereinbefore defined and characterised by a polymer flow temperature,wherein the at least one polyaromatic polymer chains have at least onereactive end group, and ii) providing at least one chain linkingcomponent having at least two linking sites as hereinbefore defined, andiii) admixing at a first temperature which is less than the chainlinking temperature at which the reactive end group and linking sitesare adapted to react as hereinbefore defined.
 23. A process as claimedin claim 22 wherein admixing is carried out at or below the compositionflow temperature employed for shaping the composition, and shaping iscarried out simultaneously or subsequently.
 24. A process as claimed inany of claims 22 and 23 wherein the polymers are prepared from monomersobtained and isolated with the use of first and second fluids in thesubstantial absence of an effective amount of azeotrope.
 25. A processas claimed in claim 24 wherein the monomers are prepared in apreselected Mn and as the monomers are in solution introducingalternative end groups by reaction in the solution prior to isolationthereof.
 26. A process as claimed in claim 24 or 25 wherein first fluidcomprises at least one dipolar aprotic solvent, optionally present in afluid mixture with other liquids or non liquids, which acts to promotethe polymerisation reaction, preferably selected from one or more ofsulphur oxides, such as sulphoxides and sulphones, formamides,pyrrolidones, cyclic ketones and the like, and the second fluid isselected from alcohols and demineralised water or demineralised aqueoussolvents and mixtures thereof.
 27. A process as claimed in any of claims24 to 26 wherein the polymer is as claimed in claims 16 to 19, whereinmonomer precursors are selected according to the desired polymercomposition comprising polyethersulphones to polyetherethersulphones ina desired ratio employing respective proportions of bisphenol anddihalides to monophenol in the same molar amounts in the range of10:90-100:0, preferably 10:90-70:30.
 28. A process as claimed in any ofclaims 24 to 27 wherein reactive end groups are introduced at the outsetwith the monomer polymer precursors.
 29. A process as claimed in any ofclaims 24 to 28 wherein end groups comprising halo or hydroxy reactivegroups are obtained by addition of an excess of a component ashereinbefore defined in claim 27 providing the repeating units of thepolyarylsulphone, for example in the form of a dihalide or a bisphenoland monophenol; alternatively end groups comprising amino reactivegroups may be obtained by addition of a pre-determined amount of amonomer, which does not provide repeating units of the polyarylsulphone,for example of aminophenol.
 30. A process for providing a composition ashereinbefore defined in any of claims 1 to 21, as a shaped article orfilm, such as impregnated, moulded, injection moulded, extruded or thelike articles or cast, sprayed or rollered films, comprising obtainingthe composition according to the invention as hereinbefore defined,subjecting to a first temperature as hereinbefore defined correspondingto the flow temperature of the unreacted composition and shapingaccording to known techniques, optionally in solution of a suitablesolvent, subjecting to a second elevated temperature as hereinbeforedefined corresponding to the temperature for chain linking reaction ofthe composition and obtaining a shaped article or film having increasednumber average molecular weight in a second range as hereinbeforedefined.
 31. A process as claimed in claim 30 wherein processingconditions comprise elevated temperature in the range of 150-400° C.more preferably 175-300° C., for example 190-250° C.
 32. A resincomposition as claimed in any of claims 1 to 21 for fabrication ofstructures, including load-bearing or impact resisting structures,containing a reinforcing agent such as fibres.
 33. A prepreg comprisinga composition as hereinbefore defined in any of claims 1 to 21 andcontinuous fibres, obtained by a process as hereinbefore defined.
 34. Acomposite comprising a pre-preg as hereinbefore defined in claim 33laminated together by heat and pressure, for example by autoclave,compression moulding, or by heated rollers, at a temperature above thecuring temperature of the polymer composition.
 35. A thermoplast or athermoplast-modified thermoset resin shaped product comprising acomposition, pre-preg, laminar composite or shaped product ashereinbefore defined in any of claims 1 to 21, 33 to 35 and, which isobtained by the method as hereinbefore defined in claim 30 or 31, foruse in transport such as aerospace, aeronautical, marine or automotiveindustries, rail and coach industries or in building/constructionindustry, or for use in non-high performance transport applications,non-construction applications and adhesive applications, including hightemperature adhesive applications.
 36. A composition, pre-preg, laminarcomposite or shaped product as hereinbefore described or illustrated inthe description and figures.